The Nightmare Before Christmas is a beloved Halloween and Christmas movie mash-up that is well-known as the brainchild of the eccentric Tim Burton. Everyone knows that Tim Burton came up with the idea for Nightmare, but did you know he was too busy filming Batman Returns to direct it, and had Henry Selickset as the director instead?

1. The Nightmare Before Christmas is based on a 3-page poem of the same name that Tim Burton wrote in 1982 while working as an animator for Disney.

2. Part of Burton’s inspiration for the poem came from television specials Rudolph the Red-Nosed Reindeer, How the Grinch Stole Christmas!, and the poem A Visit from St. Nicholas.

3. The film was originally intended to be either a short film or a 30-minute TV special, with Vincent Prince as the narrator.

4. The themes in The Nightmare Before Christmas were deemed “too weird” and Burton was later fired from his job at Disney because they had nothing left for him to do.

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5. Jack Skellington first appeared in Tim Burton’s film Beetlejuice in 1988, on top of the title character’s carnival hat.

6. Patrick Stewart did the original opening for the film, but was cut for unexplained reasons, and his narration can be heard on the soundtrack.

7. The film used over 230 sets, all set up in 19 different sound stages.

8. It took a group of about 100 people 3 years to complete this movie. For every one second of film, up to 12 stop-motion moves had to be made.

9. Using stop-motion animation, it took a week to film just one minute of tape.

10. Danny Elfman wrote the songs and music for the film without having a script. He’s said it was “one of the easiest jobs I’ve ever had. I had a lot in common with Jack Skellington.”

11. Chris Sarandon (yes, Susan Sarandon‘s brother) was the voice of Jack Skellington, but could not sing. Elfman stepped in to provide Jack’s singing voice. As well as the voices of Barrel and the Clown with the Tear-Away Face.

12. Zero’s nose is not red, but in fact a tiny glowing jack-o-lantern.

13. Oogie Boogie was originally meant to be Dr. Finklestein in disguise but it was changed before filming. Reportedly, Tim Burton was so infuriated by this idea that he kicked a hole in a wall.

14. When Jack delivers presents to the children, some of the gifts are nods to other Tim Burton films. There is a snake that looks like a Sandworm from Beetlejuice, as well as a shrunken head from the “afterlife waiting room”. The Cat and Duck are both featured in Batman Returns.

15. They began filming Nightmare before the script was even finished.

16. Disney fought very hard for Jack to have eyes. When those involved in the creation of Jack didn’t budge, Disney chose to release Nightmare under Touchstone Pictures, as the film seemed too off-brand for their logo.

17. The hardest shot in the entire film is of Jack opening a door. While filming in stop-motion, they were working to keep the film as live-action as possible, so in order to get an exact reflection of Jack’s hand opening the golden knob leading to Christmas Town it was a painstakingly difficult process.

18. Tim Burton had plans for making a sequel, with the working title “The Unlucky Clover” but never managed to get it to theaters because he said it would “spoil the magic of the first movie.”